I'm much more a winter person than a summer. Simply put, I don't like being too hot. But I do actually like the sunshine.
So, my favourite days are the ones you sometimes get in winter, when the air is freezing cold but the sun is bright in a cloudless sky. When it's pleasant to go out for a walk, albeit bundled up warm, but when your breath fogs in the air, and your footsteps lighty crunch through the light frost.
Conversely, you get days like today, when it is hot and sticky, but the sky is horribly overcast and it's miserable and wet. Those are probably the days I like least, being the worst of all possible worlds.